The Kyoto Protocol is an international agreement that aims to reduce greenhouse gas emissions and combat climate change. It also includes provisions to reduce air pollution by setting limits on emissions of sulfur dioxide, nitrogen oxides, and other pollutants.

The Clean Air Act is a comprehensive federal law that regulates air emissions from stationary and mobile sources. Its primary goal is to protect human health and the environment from air pollution.

Sulfur dioxide is a major air pollutant that is emitted from power plants, industrial facilities, and other sources. When sulfur dioxide reacts with water in the atmosphere, it forms sulfuric acid, which is a major component of acid rain.

Air pollution control is the process of removing pollutants from the air before they are released into the atmosphere. This can be done using a variety of methods, such as scrubbers, filters, and catalytic converters.

The United Nations Environment Programme (UNEP) is the leading global environmental authority that sets the global environmental agenda, promotes the coherent implementation of the environmental dimension of sustainable development within the United Nations system, and serves as an authoritative advocate for the global environment.

An emission limit is the maximum amount of a pollutant that is allowed to be emitted from a source. Emission limits are typically set by regulatory agencies to protect human health and the environment.

Ground-level ozone is a major air pollutant that is formed when sunlight reacts with nitrogen oxides and volatile organic compounds (VOCs). Smog is a type of air pollution that is characterized by high levels of ground-level ozone and other pollutants.

Cap and trade is a program that allows sources to trade emission allowances. Under a cap and trade program, a limit (or cap) is set on the total amount of a pollutant that can be emitted. Sources are then issued allowances that allow them to emit a certain amount of the pollutant. Sources can trade allowances with each other to meet their emission limits.

Particulate matter is a major air pollutant that consists of small particles of solid or liquid matter suspended in the air. Particulate matter can cause a variety of respiratory problems, including asthma, bronchitis, and lung cancer.

A percent reduction requirement is a program that requires sources to reduce their emissions by a certain percentage. Percent reduction requirements are typically used to achieve specific air quality goals.

Carbon dioxide is a major greenhouse gas that is emitted from a variety of sources, including power plants, industrial facilities, and transportation. Carbon dioxide is the primary air pollutant responsible for causing climate change.

An incentive-based program is a program that provides financial incentives to sources to reduce their emissions. Incentive-based programs can take a variety of forms, such as tax breaks, subsidies, and grants.

The Paris Agreement is an international agreement that aims to reduce emissions of greenhouse gases and combat climate change. The agreement was adopted by 196 countries at the 21st Conference of the Parties (COP21) to the United Nations Framework Convention on Climate Change (UNFCCC) in Paris, France, on 12 December 2015.

A technology-based program is a program that requires sources to use specific technologies to reduce their emissions. Technology-based programs are typically used to achieve specific air quality goals.

Chlorofluorocarbons (CFCs) are a group of greenhouse gases that are also responsible for ozone depletion. CFCs are used in a variety of products, including refrigerators, air conditioners, and aerosol cans. The production and use of CFCs has been phased out under the Montreal Protocol.